The senior Tory was quizzed by moderator Mishal Husain over why the policy document was not fully costed. "Judge us on our record," Rudd declared, with some members of the public bursting into laughter.

The seven-way debate, including Ukip leader Paul Nuttall and Green co-leader Caroline Lucas, comes just over a week before the general election on 8 June.

But Prime Minister Theresa May has refused to take part in the TV event. Labour leader Jeremy Corbyn had said he would not participate in such debates unless May was present. However, the left-winger dramatically U-turn on the vow and took part in the BBC debate.